Method for the construction of a cut-off wall



C. VEDER May 14, 1957 METHOD FOR THE CONSTRUCTION OF' A CUT-OFF' WALL Filed Nov. 22, 1950 2 Sheets-Sheet 1 T May 14, 1957 c. VEDER 2,791,886

`\ METHOD FOR THE CONSTRUCTION OF A OUT-OFF WALL Filed Nov. 22, 1950 2 Sheets-Sheet 2 INVENToR. CHRISTIAN VEDER ATTORNEY F/G. a 2

" as to form a single homogeneous mass.

` by drilling a series of intersecting holes, preferably made United rates atet METHOD FOR THE CONSTRUCTION F A CUT-OFF WALL Christian Veder, Milan, Italy, assigner to I. C. 0. S. Impresa Costruzioni Opere Specializzate, Milan, Italy Application November V22, 1950, Serial No. 196,978

' Claims priority, application Italy May 30, 1950 7 Claims. (Cl. 61-31) This invention relates to cut-ofi walls and more particularly to a method for the construction of a cut-off wall.

Methods for the construction of lwatertight walls in the ground are already known, for example for the construction ofcut-of'f walls, which eliminate the necessity of expensive draining and sealing operations during eX- cavations, especially in alluvial grounds.

The processes used up to now consist either in inserting into the ground pre-fabricated elements, laterally inter-connected, or in drilling iinto the ground, by means of metallic boring, tubes, a succession of bores placed adjacent each other, which bores are subsequently filled with cement and thus form a concrete cut-off wall or palisade.4 Alternatively, there may be inserted into these bores cement poles, pre-fabricated to define a particular shape or section, which poles establish a more intimate interlocking connection between the single elements of the palisade.; A

Walls so built do not, however, always ensure the desired watertightness. The reason for this is partly because it is difficult to obtain a` perfect interlocking or interengagement of the single elements, partly because ordinary methods of drilling by means of boring tubes do not guarantee a perfect verticalness of the final wall, and partly because the manner in which'the drilling is normally effected by the tubes disintegrates, loosens and possibly washes away the soil in the vicinity of the wall of the bores in such a way that supplementary injection operations are necessary in order to consolidate the wall and :to fill in the empty spaces. Anyway, `in constructing a wall in accordance -wit known methods, a depth of about 20 metres only can be obtained, because beyond thisdepth the diameters of the boring tubes have to be made smaller, and consequently no interengagement of the individual elements is attained below this depth. A

These drawbacks are avoided by building up the wall according to the present invention. A wall constructed in accordance with this invention consists of a series of substantially vertical cylindrical elements which intersect, interengage and adapt themselves to each other so This is obtained with a rotary drill bit, which holes are lled on the spot with cement or the like material.

it is possible to build up such a watertight Wall in two ways. The first one comprises drilling one or more holes in spaced relation, and then filling these holes with concrete made of a sufficiently slow setting cement, in order to be able to drill intermediate holes intersecting the partially set concrete poles already present -in the rst mentioned hole or holes without meeting with excessive resistance by these partially set poles, and in order that the concrete then filled into the intermediate holes may intimately bind itself to the concrete in the first mentioned holes.

The second embodiment of the method of building up the cut-off Wall, which is also within the scope of the l: Il. L

present invention, comprises the filling with gravel of one or more suitably -spaced holes drilled into the ground, whereafter intermediate and adjacent holes are drilled, which latter intersect the first mentioned holes and are likewise filled with gravel, and finally injecting into the mass of gravel contained in all said holes a cement slurry that will transform the gravel into concrete.

In order that the invention may be better understood several embodiments of the inventive construction method are given in detail in the following description to be read with reference to the accompanying drawing-s that illustrate the two above cited methods as examples to which' examples, however, the present invention is not limited.

In the drawings:

Fig. l is a vertical section of a first hole drilled into `the ground with the drilling tool still in position;

Fig. 2 is a vertical section of the first element of the palisade or cut-ofi wall built according to the iirst method of construction;

Fig. 3 is a vertical section showing the building up of the second element, ,also according to the first method of construction;

Fig. 4 is a vertical section of a portion of the palisade or cut-off' wall completed in conformity with the tirst method of construction;

Fig. 5 is a vertical section of a first element in the process of construction of the palisade or cut-off wail in conformity with the second method of construct-iong'.

Fig. 6 is a vertical section of a first element and of a portion of the hole for a second element of the palisade or'cut-off wallaccording to the second method of -conl struction;

Figs. 7 and 8 show in vertical section' the beginning and the end of a further stage of construction of the pal-isadeV or cut-off wall according to the second method of construction;

Fig. 9 is a horizontal section 4of` a completed cut-off fwall constructed in accordance with any method according -to the invention; Y Fig. lO is a horizontallsection illustrating an intermediate step during the building-up `of a cut-off wall ac'- cording to the invention; and

Fig. 1l is a horizontal section illustrating a subsequent` j intermediate step during the building-up of a cut-off'wall,`

according to the invention.

the direction of the arrow 3, in order to carry the material dug out from the bottom of the hole up to the surface and to obtain at the same time sealing and reinforcement of wall 4; as liquid for example a suspension of bentonite ,and water may be used.

By proceeding according to the first method of construction, one lls the first hole 2 with concrete 5 of slow setting quality (Fig. 2) and subsequently the second hole 2a (see Fig. 3) is drilled adjacently in a similar way. Along the line of intersection of the two holes an impermeable layer 6 is formed, which, if permitted to remain, would interrupt the continuity of the palisade; in order to avoid this drawback, this layer 6, that has formed itself in the line of contact with the concrete of the first element is washed away, using pure water instead of the thick liquid. The light sealing and reinforcing layer, however, that has been incorporated into the natural soil wall of the second hole 2a remains unchanged. By continuing this process any desired number of times, a complete- 1y watertight cut-off wall is obtained, as shown in the vel.'-

tical :section of Eig. 4 kandthe horizontal section of Fig. 9, Ycompletely surrounded by an impermeable layer 4.

It is obvious that the boring of the first element as well as of the following ones, which latter intersect with those already filled with concrete, may be carried out by means of metallic tubes instead of by rotary drill bits; one should take care that the metallic tubes are held in a perfect vertical position during the drilling operation.

By proceeding in accordance with the second method of construction, the first ho-le 2 is lled up with pure gravel 7 (Fig. 5), the second hole 2a (Fig. 6) being afterwards bored in the same way as shown for the first method of construction. Y Y

A compact palisade or cut-olf wall is thus obtained which is formed by a mass of gravel 7 into which a slurry of cement is injected by means of small metallic pipes 8 which are pushed into the gravel down to the bottom of the palisade or cut-off wall and are afterwards pulled back gradually (Figs. 7 and 8), thus transforming the mass of gravel into a compact mass of concrete 9.

The result of this is a compact palisade or cut-off wall as represented by Figs. 4 and 9. According to above description of both methods of construction the individual holes 2, 2a, 2b of the entire series of holes are drilled in consecutive order. It is obvious that one will not go out of the scope of the invention if the order of drilling the holes is modified; it might be advantageous, especially in order to accelerate `the work, instead of drilling the holes consecutively, to make at first a series of spaced holes 2, 2b, 2d (Fig. 10) whose axes are at a distance x smaller than twice their diameter d, and to make afterwards a second series of Vspaced holes 2a, 2c (Fig. 11), the axes of which are in the center between the axes of the rst series of holes 2, 2b, 2d in order to be able to work with several drillers at the same time.

What I claim is:

`1. A method for the construction of a cut-off wall, comprising the steps of: drilling into the natural soil a series of vertical holes in such a way, that a first hole and a second hole of two adjacent holes are drilled 'at different times, spacing the vertical axes of adjacent holes of said series of holes from each other at a distance smaller than the sum of the radii of said adjacent holes whereby adjacent holes intersect each other, consolidating the wall of each hole and rendering same impervious to water by introducing into the hole a thickish liquid apt to gel, causing said thickish liquid to circulate for a predetermined time in each of said holes from the bottom towards the top whereby material loosened by the drilling is removed, filling the first hole of two adjacent holes with a slowly binding cementitious material and performing the subsequent drilling of the second hole of two adjacent holes while the cementitious material filled into said first hole is still in binding condition, removing excess thickish liquid and loosened material from each hole after the drilling thereof, washing off a layer of impermeable material formed by said thickish liquid at the intersection of adjacent holes on the surface of the incompletely bound cementitious material filledinto the first hole of two adjacent holes, and filling thereafter cementitious material into the second hole of two adjacent holes.

2. A method for the construction of a cut-olf wall as claimed in claim 1, wherein the holes'of the series of holes are drilled in consecutive order.

3. A method for the construction of a cut-off wall as claimed in claim l, wherein at first a first plurality 0f spaced holes is drilled and `thereafter a second plurality of spaced holes is drilled, and wherein the drilling of said holes is carried out in such a manner that the axes of the holes of said second plurality of spaced holes are arranged in the center between the axes of the holes of said first plurality of spaced holes.

4. A method for the construction of a cut-off wall as claimed in claim 1, wherein after the circulation of said thickish liquid in the hole water is introduced into said hole for removing the excess thickish liquid and the loosened material and for Washing off said layer of impermeable material.

5. A method for the construction of a cut-off wall as claimed in claim l, wherein said thickish liquid is introduced into the hole during the drilling of the latter.

6. A method for the construction of a cut-off wall as claimed in claim l, wherein the drilling of the holes is carried out by means of rotary drill bit means having an axial bore, and wherein said thickish liquid is introduced into the hole through said axial bore of the rotary drill bit means.

7. A method for the construction of a cut-off wall as claimed in claim 1, wherein a bentonite mud is used as said thickish liquid.

References Cited in the file of this patent UNITED STATES PATENTS 814,240 Smith Mar. 6, 1906 1,665,798 Sipe Apr. 10, 1928 1,909,980 Newman May 23, 1933 1,991,637 Hann Feb. 19, 1935 2,027,511 Bertran Jan. 14, 1936 2,329,223 Schmidt Sept. 14, l19453 2,539,670 Ognibene e Jan. 30, 1951 2,555,359 Montague June 5, 1951 FOREIGN PATENTS 303,685 Great Britain Jan. 10, 1929 353,490 Italy Oct. 19, 1937 455,110 Italy Feb. 14, 1950 

